SCSS

HTML

<table>
  <colgroup>
    <col style="max-width: 100px" />
    <col span="2" style="width: 75px;" />
    <col style="width: auto" />
  </colgroup>
  <thead>
    <tr>
      <td>Col A</td>
      <td>Col B</td>
      <td>Col C</td>
      <td>Col D</td>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>foo</td>
      <td>foo</td>
      <td>foo</td>
      <td>foo</td>
    </tr>
    <tr>
      <td>foo</td>
      <td>foo</td>
      <td>foo</td>
      <td>foo</td>
    </tr>
  </tbody>
</table>

SCSS

table {
  table-layout: fixed;
  width: 100%;
  border-collapse: collapse;
  td {
    padding: 2px;
    border: 1px solid black;
  }
}